Roof bolters are drilling operators who drill holes in the arched roofs of mining tunnels and install bolts in the form of metal cores and plastic fillers to reinforce the roof to prevent collapse. This avoids cumbersome scaffolding supports and framing. Previous roof drilling systems have required the operator to guide the rotating drill with one hand while supporting the assembly with the other hand at least until the drill is started. Numerous accidents have dictated the necessity for a structure which avoids the need for hand guiding of the rotating bit.
An example of a roof drilling system is illustrated in U.S. patent to Leibee and Oaks, U.S. Pat. No. 3,519,091, issued July 7, 1970.
It is, therefore, an object of the present invention to provide a rugged drill bit which has wall strength to withstand the rigours of the drilling, with interior and coolant passages which permit maximum coolant volume while preventing the plugging of the passages.
It is a further object to provide a drive system which has maximum drive surface, thus giving the necessary axial stability while providing ample drive contact.
A still further object is the provision of interior coolant passages which allow free flow of the fines and chips resulting from the drilling operation.
Other objects and features of the invention will be apparent in the following description and claims in which the principles of the invention are set forth together with details of structure and operation, all in connection with the best mode presently contemplated, which will enable a person skilled in the art to practice the invention.